Localisation and lesion recognition at Colonoscopy

The ileo-caecal valve is the only definite anatomical landmark in the colon. It may occasionally be difficult to find

The internal appearance of transverse colon is usually triangular. However the descending colon may look triangular or the transverse colon may look circular

There may be bluish/grey indentation from the liver at the hepatic flexure; however a similar appearance may sometimes occur at the splenic flexure.

The distance of the lesion should only be mentioned on withdrawal. So you could say that the lesion/polyp was at 30cms in the sigmoid colon on withdrawal. The scope distance information at insertion is meaningless due to the elasticity of the colon

For the above difficulties of localisation, any area which may need repeat inspection or treatment should be tattooed.

Lesion recognition

Normal colonic mucosa shows a fine, ramifying vascular pattern.

Mucosal lesions- The vascular pattern is lost in marked hyperaemia as in IBD.

There are 9 different endoscopic indices of activity for ulcerative colitis (UC) developed for clinical trials; none have been validated. All 9 indices are subject to interobserver variation (IOV).

The typical endoscopic features of Crohn’s disease are the discontinuos spread of the disease, lesions are distributed asymmetrically. There may be bizarre, ‘map-like’ necroses and fissures. Appearances of so called ‘snail tracks’, aphthoid ulcers etc

Malignant polyp- is suspected if the polyp is irregular, ulcerated or thick walled. Firmness to palpation with a snare tube is probably the best discriminant for a malignant polyp. If malignancy is suspected, transect low in the stalk and tattoo the area.